The present invention relates generally to devices for measuring the viscosity of a fluid, and more particularly to a device for testing a fluid sample contained in a cylindrical tube.
Fluids used in processing or manufacturing are often packaged and shipped in bulk. Cartridges containing small batch samples useful for quality control testing may be provided along with the bulk material. For example, a supplier of liquid urethane, which is typically purchased in fifty gallon drums, may also provide a cartridge containing a sample of the batch material contained in the drum.
Heretofore, the material contained in the cartridge was placed in a pressure flow viscometer cup for testing. One drawback associated with this procedure is that it requires the direct handling of the sample material and exposes the material to air and other elements during testing. The exposure of the sample to air causes the partial curing and contamination of the material, which can affect test results.
Furthermore, the devices for testing viscosity typically employ a "floating" piston, which extrudes the sample through an orifice of known diameter under a given pressure. The output is weighed and the viscosity of the material is determined. Because currently available devices involve the handling of the material during testing, meticulous cleaning of the equipment is required to maintain consistency in testing.
It will be appreciated by those skilled in the art that it is desirable to have a device for testing the viscosity of a the fluid in a container. To this end, there have been several attempts to devise such devices.
One such attempt was disclosed in U.S. Pat. No. 2,426,393, issued to Fischer, which is incorporated by reference as if fully set forth herein. The Fischer device is directed to an inline viscometer for determining the viscosity of a fluid in motion. The device comprises a rotameter tube wherein are disposed two separate metering floats. One float is insensitive to, and unaffected by, variations in viscosity so that its position is determined solely by the rate of flow of the fluid. The other float is sensitive to, and affected by, variations in both viscosity and rate of flow. Accordingly, the viscosity of the flowing fluid may be determined by the difference in the positions of the two metering floats and the variations in the fluid viscosity can be determined by the corresponding variations and the difference of the position of the two floats.
U.S. Pat. No. 5,388,447, issued to Fitch, et al., is directed to a viscosity measurement apparatus for measuring viscosity of a fluid under known pressure. A fluid sample passes through a tube of known diameter and length. A piston, sealably engaged with a closed chamber, which is in fluid communication with the tube, may be moved by force of the fluid passing through the tube. A linear gage measures the time required to move the piston. A mechanism is provided to reset the piston by forcing fluid back through the tube to empty the chamber to begin another measurement. The device may be attached to a sampling valve of a fluid system under pressure.
Japanese Patent No. 58/21542, issued to Yamada, is directed to a flow testing device comprising a cylinder having a nozzle at its lower end and a plunger positioned within the cylinder for extruding the fluid sample through the nozzle.
Further, the list that follows includes patents directed to other viscosity measuring devices.
______________________________________ Patent No. Inventor ______________________________________ 1,989,050 Albersheim, et al 2,011,862 Konheim, et al 3,195,351 Feldman ______________________________________
While the patents referenced hereinabove generally disclose devices for testing the viscosity of a fluid, none discloses a viscometer configured to enable direct testing of a fluid contained in a cartridge. What is needed then, is a viscometer that enables the testing of the fluid contained in a cartridge without requiring that the sample be handled or transferred to a testing device, thereby exposing the sample to air, which affects the consistency of the fluid and exposes the sample to airborne contaminants.